Where I am now, and where I used to live in Gippsland and the Snowies, our cryptofauna is mostly big cats, some of which may or may not be released American mascot pumas from troops stationed here in WW2, relict Tasmanian tigers (Thylacine), feral cats or dogs grown huge (John Walmsley of Warrawong Sanctuary used to have over his fireplace the skin of such a cat which he had shot, which was easily six feet long, and I've seen cats as big in the Dandenongs and the Snowies.). Relict Thylacoleo (marsupial lions) have also been suggested, but I've no idea how possible that is, they are meant to be extinct.
The Merigalah Monster, from the mountains in NSW, I suspect to be another big cat, what sort I've no idea, but I have seen one of its fresh kills. That was a big buck kangaroo, neck cleanly broken, back scratched up, guts and part of the shoulder eaten. We were very careful about our camp that night, I can tell you! That country is so wild, precipitous and broken up that anything could be in there.
The so-called Tantanoola Tiger, when somebody finally shot it, turned out to be an ancient and mangy Siberian wolf. How it got to southern Australia I've no idea, but Tantanoola being on the Shipwreck Coast, quite likely it came from a wrecked ship. The wolf was stuffed and was in the Tantanoola pub for years. But that country was at the time so empty that it may well have passed unnoticed, had it not started killing sheep, poor thing.
Ask Purple Wyrm about cryptofauna, I believe he also has an interest in the subject.